Basic errors in the structure and function of extracellular matrix (or its specialized form basement membrane) leads to a broad spectrum of problems related to developmental abnormalities and secondary complications in such diseases as diabetes mellitus where basement membrane thickening and dysfunction is observed. Our understanding of the cellula mechanisms underlying normal and abnormal basement membrane formation and the role of matrix components in signal transmission during development has been limited by a lack of appropriate in vitro and in vivo models to experimental approach these problems. In order to better approach these problems, we have developed an in vivo cellular model in which basement membrane formation can be experimentally induced between an epithelial bilayer and its formation related to 1) the process of cytodifferentiation and morphogenesis and 2) disease processes which lead to abnormalities in the structure and function of basement membranes. This model has been developed from the invertebrate, Hydra vulgaris which is structurally reduced to an epithelial bilayer with an intervening basement membrane (mesoglea). Building on previously published studies, we have defined experimental conditions in which 1) pellets generated from cells isolated from adult Hydra form an epithelial bilayer, deposit an intervening basement membrane, and subsequently reform an adult Hydra structure within 72-96 hr through the processes of cytodifferentiation and morphogenesis and 2) as related to the disease diabetes mellitus, development of this cell-aggregation-morphogenesis system in the presence of elevated glucose levels leads to an abnormal thickening of basement membrane within 72-96 hr time frame as opposed to months or years as required in mammalian animal model of diabetes. Utilizing this in vivo epithelial/basement membrane model system we propose to test hypotheses directed at the cellular mechanisms involved in the normal and abnormal development of basement membrane and the concomitant transmission of epithelial signal which are involved in tissue cytodifferentiation and morphogenesis. Using a combination of cellular and molecular biology approaches we propose to focus on the following specific aims in order to further develop this nonmammalian in vivo model for application to biomedical research: 1. To examine the process of normal basement membrane formation during development and determine the precise role of basement membrane protein domains in tissue cytodifferentiation and morphogenesis. 2. To examine cellular mechanisms by which elevated glucose levels lead to an abnormal thickening of basement membrane as observed in individuals with diabetes mellitus.